The DAF-16 FOXO transcription factor regulates natc-1 to modulate stress resistance in Caenorhabditis elegans, linking insulin/IGF-1 signaling to protein N-terminal acetylation

• Published in: PLoS genetics Vol. 10; no. 10; p. e1004703
• Main Authors: Warnhoff, Kurt, Murphy, John T, Kumar, Sandeep, Schneider, Daniel L, Peterson, Michelle, Hsu, Simon, Guthrie, James, Robertson, J David, Kornfeld, Kerry
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.10.2014; Public Library of Science (PLoS)
• Subjects: Acetylation; Acetyltransferases; Amino Acid Sequence; Animals; Animals, Genetically Modified; Biology and life sciences; Caenorhabditis elegans; Caenorhabditis elegans - drug effects; Caenorhabditis elegans - genetics; Caenorhabditis elegans - metabolism; Caenorhabditis elegans - physiology; Caenorhabditis elegans Proteins - genetics; Caenorhabditis elegans Proteins - metabolism; Cellular signal transduction; Forkhead Transcription Factors - genetics; Forkhead Transcription Factors - metabolism; Gene Expression Regulation, Developmental; Genetic aspects; Genetic regulation; Genetic research; Health aspects; Insulin; Insulin - metabolism; Insulin-Like Growth Factor I - metabolism; Kinases; Ligands; Molecular Sequence Data; Mutation; N-Terminal Acetyltransferase C - genetics; N-Terminal Acetyltransferase C - metabolism; Nematodes; Proteins; Research and Analysis Methods; Signal Transduction; Stress (Physiology); Stress response; Stress, Physiological; Studies; Transcription factors; Zinc; Zinc - metabolism; Zinc - toxicity
• DOI: 10.1371/journal.pgen.1004703
• ISSN: 1553-7404; 1553-7390

The insulin/IGF-1 signaling pathway plays a critical role in stress resistance and longevity, but the mechanisms are not fully characterized. To identify genes that mediate stress resistance, we screened for C. elegans mutants that can tolerate high levels of dietary zinc. We identified natc-1, which encodes an evolutionarily conserved subunit of the N-terminal acetyltransferase C (NAT) complex. N-terminal acetylation is a widespread modification of eukaryotic proteins; however, relatively little is known about the biological functions of NATs. We demonstrated that loss-of-function mutations in natc-1 cause resistance to a broad-spectrum of physiologic stressors, including multiple metals, heat, and oxidation. The C. elegans FOXO transcription factor DAF-16 is a critical target of the insulin/IGF-1 signaling pathway that mediates stress resistance, and DAF-16 is predicted to directly bind the natc-1 promoter. To characterize the regulation of natc-1 by DAF-16 and the function of natc-1 in insulin/IGF-1 signaling, we analyzed molecular and genetic interactions with key components of the insulin/IGF-1 pathway. natc-1 mRNA levels were repressed by DAF-16 activity, indicating natc-1 is a physiological target of DAF-16. Genetic studies suggested that natc-1 functions downstream of daf-16 to mediate stress resistance and dauer formation. Based on these findings, we hypothesize that natc-1 is directly regulated by the DAF-16 transcription factor, and natc-1 is a physiologically significant effector of the insulin/IGF-1 signaling pathway that mediates stress resistance and dauer formation. These studies identify a novel biological function for natc-1 as a modulator of stress resistance and dauer formation and define a functionally significant downstream effector of the insulin/IGF-1 signaling pathway. Protein N-terminal acetylation mediated by the NatC complex may play an evolutionarily conserved role in regulating stress resistance.